// PCIe Extension Riser Board Holder
// Configurable 3D printable holder with M3 mounting holes

// === Design Parameters ===
thickness = 3;           // Thickness of the holder (configurable)
hole_diameter = 2.8;     // M3 hole diameter (slightly smaller for 3D printing)
margin_x = 8;            // Margin on each side of the holes
margin_y = 6;            // Margin above and below the holes (currently unused)
holder_width = 6;       // Width of the rectangular plane

// === Hole Spacing Parameters ===
first_hole_spacing = 20.5;   // Distance from first to second hole
second_hole_spacing = 20.5;  // Distance from second to third hole
third_hole_spacing = 22;     // Distance from third to fourth hole

// === Technical Parameters ===
cylinder_overlap = 0.1;      // Small overlap to ensure clean boolean operations
cylinder_resolution = 32;    // Number of facets for cylinders (higher = smoother)
preview_cylinder_height = 2; // Height of preview cylinders
preview_cylinder_diameter = 3; // Diameter of preview cylinders

// === 2020 Extrusion Insert Parameters ===
extrusion_2020_outer = 20;      // 2020 extrusion outer dimension
extrusion_2020_inner = 16.2;    // Internal cavity dimension
extrusion_2020_slot_width = 6;  // T-slot opening width
extrusion_2020_slot_depth = 1.8; // T-slot depth from outer edge
tab_clearance = 0.2;            // Clearance for tabs to fit in T-slots
insert_clearance = 0.1;         // General clearance for the insert body

// === 2020 Extrusion Insert Module ===
module extrusion_2020_insert_2d(
    with_tabs = true,           // Include tabs for T-slot engagement
    tab_width = 4,              // Width of each tab
    tab_thickness = 1.6,        // Thickness of tabs (fits in T-slot depth)
    insert_width = 15.8,        // Width of main insert body (with clearance)
    insert_height = 15.8,       // Height of main insert body (with clearance)
    tab_positions = [0.25, 0.75], // Relative positions of tabs (0-1)
    corner_radius = 0.5         // Corner radius for smoother printing
) {
    
    // Calculate dimensions
    effective_insert_width = insert_width;
    effective_insert_height = insert_height;
    
    // Main insert body
    difference() {
        // Create main rectangular body with rounded corners
        offset(r = corner_radius) 
            offset(r = -corner_radius)
                square([effective_insert_width, effective_insert_height], center = true);
        
        // Optional cutouts can be added here for weight reduction or specific features
    }
    
    // Add tabs for T-slot engagement if requested
    if (with_tabs) {
        // Top tabs
        for (pos = tab_positions) {
            translate([
                (pos - 0.5) * effective_insert_width,
                effective_insert_height/2 + tab_thickness/2
            ])
                square([tab_width, tab_thickness], center = true);
        }
        
        // Bottom tabs
        for (pos = tab_positions) {
            translate([
                (pos - 0.5) * effective_insert_width,
                -(effective_insert_height/2 + tab_thickness/2)
            ])
                square([tab_width, tab_thickness], center = true);
        }
        
        // Left tabs
        for (pos = tab_positions) {
            translate([
                -(effective_insert_width/2 + tab_thickness/2),
                (pos - 0.5) * effective_insert_height
            ])
                square([tab_thickness, tab_width], center = true);
        }
        
        // Right tabs
        for (pos = tab_positions) {
            translate([
                effective_insert_width/2 + tab_thickness/2,
                (pos - 0.5) * effective_insert_height
            ])
                square([tab_thickness, tab_width], center = true);
        }
    }
    
    // Display insert specifications
    echo("=== 2020 Extrusion Insert Specifications ===");
    echo(str("Insert dimensions: ", effective_insert_width, "mm x ", effective_insert_height, "mm"));
    echo(str("Tab width: ", tab_width, "mm"));
    echo(str("Tab thickness: ", tab_thickness, "mm"));
    echo(str("Tabs enabled: ", with_tabs));
    echo(str("Tab positions: ", tab_positions));
    echo("=== End Insert Specifications ===");
}

// === Function to create 3D insert from 2D profile ===
module extrusion_2020_insert_3d(
    length = 50,                // Length to extrude the insert
    with_tabs = true,
    tab_width = 4,
    tab_thickness = 1.6,
    insert_width = 15.8,
    insert_height = 15.8,
    tab_positions = [0.25, 0.75],
    corner_radius = 0.5
) {
    linear_extrude(height = length)
        extrusion_2020_insert_2d(
            with_tabs = with_tabs,
            tab_width = tab_width,
            tab_thickness = tab_thickness,
            insert_width = insert_width,
            insert_height = insert_height,
            tab_positions = tab_positions,
            corner_radius = corner_radius
        );
}

// === Main Function ===
module pcie_riser_holder(
    thickness = 3,
    hole_diameter = 2.8,
    margin_x = 8,
    holder_width = 12,
    first_spacing = 20.5,
    second_spacing = 20.5,
    third_spacing = 22,
    show_preview_holes = false
) {
    // Calculate hole positions
    hole_position_1 = 0;
    hole_position_2 = hole_position_1 + first_spacing;
    hole_position_3 = hole_position_2 + second_spacing;
    hole_position_4 = hole_position_3 + third_spacing;
    
    hole_positions = [
        hole_position_1,
        hole_position_2,
        hole_position_3,
        hole_position_4
    ];
    
    // Calculate total dimensions
    total_length = hole_position_4 + (margin_x * 2);
    total_width = holder_width;
    
    // Main holder body
    difference() {
        // Create the main rectangular plane
        cube([total_length, total_width, thickness]);
        
        // Create M3 holes
        for (i = [0 : len(hole_positions) - 1]) {
            translate([margin_x + hole_positions[i], total_width/2, -cylinder_overlap])
                cylinder(
                    h = thickness + (cylinder_overlap * 2), 
                    d = hole_diameter, 
                    $fn = cylinder_resolution
                );
        }
    }
    
    // Optional preview holes for reference
    if (show_preview_holes) {
        for (i = [0 : len(hole_positions) - 1]) {
            translate([margin_x + hole_positions[i], total_width/2, thickness])
                cylinder(
                    h = preview_cylinder_height, 
                    d = preview_cylinder_diameter, 
                    $fn = cylinder_resolution
                );
        }
    }
    
    // Display specifications
    echo("=== PCIe Riser Holder Specifications ===");
    echo(str("Total dimensions: ", total_length, "mm x ", total_width, "mm x ", thickness, "mm"));
    echo(str("Hole spacing: ", first_spacing, "mm, ", second_spacing, "mm, ", third_spacing, "mm"));
    echo(str("Hole positions: ", hole_positions));
    echo(str("Hole diameter: ", hole_diameter, "mm (for M3 bolts)"));
    echo("=== End Specifications ===");
}

// === Usage Examples ===

// Generate the PCIe riser holder
pcie_riser_holder(
    thickness = thickness,
    hole_diameter = hole_diameter,
    margin_x = margin_x,
    holder_width = holder_width,
    first_spacing = first_hole_spacing,
    second_spacing = second_hole_spacing,
    third_spacing = third_hole_spacing,
    show_preview_holes = false  // Set to true to see hole positions in preview
);

// Uncomment below to generate a 2020 extrusion insert instead
// Example 1: 2D profile for manual extrusion
//extrusion_2020_insert_2d();

// Example 2: 3D insert with 50mm length
//extrusion_2020_insert_3d(length = 50);

// Example 3: Insert without tabs (for loose fit)
//extrusion_2020_insert_3d(length = 30, with_tabs = false);

// Example 4: Custom tab configuration
//extrusion_2020_insert_3d(
//    length = 40,
//    tab_width = 6,
//    tab_positions = [0.2, 0.8],
//    insert_width = 15.5,
//    insert_height = 15.5
//);